4-Amino-3,5-dichloropyridinium 3-hydroxypicolinate monohydrate

The title hydrated salt features a dense array of hydrogen bonds, forming a three-dimensional network.

In the title hydrated salt, C 5 H 5 Cl 2 N 2 + •C 6 H 4 NO 3 À •H 2 O, the pyridine N atom of the cation is protonated and an intramolecular O-H� � �O hydrogen bond is observed in the anion, which generates an S( 6) ring.The crystal packing features N-H� � �N, O-H� � �O, N-H� � �O, C-H� � �Cl and C-H� � �O hydrogen bonds, which generate a three-dimensional network.

Structure description
4-Aminopyridine and its derivatives are used clinically to treat Lambert-Eaton myasthenic syndrome and multiple sclerosis because they block potassium channels, which prolongs action potentials and increases transmitter release at the neuromuscular junction (Judge & Bever, 2006).Picolinic acid, which contains N and O donors, has attracted much attention for the design and synthesis of self-assembling systems (e.g., Steiner, 2002).In this regard, 3-hydroxypicolinic acid is of interest because it can be used as a neutral ligand or, depending on the pH value, as an anionic or cationic ligand.In addition, due to the arrangement of its functional groups, it can act as a monodentate or bidentate ligand, which allows it to form five-or six-membered chelate rings.As part of our work in this area, we now report the synthesis and structure of the title hydrated molecular salt.

Synthesis and crystallization
A hot methanol solution of 3-hydroxy picolinic acid (40 mg) was mixed with a hot aqueous solution of 4-amino 3,5-dichloro pyridine (34 mg).The mixture was cooled slowly and kept at data reports

Figure 2
One-dimensional supramolecular hydrogen-bonded chain mediated by water molecules in the title compound.

Special details
Geometry.All esds (except the esd in the dihedral angle between two l.s.planes) are estimated using the full covariance matrix.The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry.An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s.planes.Refinement.The water H atoms were located in a difference Fourier map and allowed to refine freely.The remaining H atoms were positioned geometrically (C-H = 0.93 and N-H = 0.86 Å) and were refined using a riding model, with U iso (H) = 1.2 U eq (C).

Figure 3
Figure 3Crystal packing viewed down [100] in the title compound.

Figure 1
Figure 1The molecular structure of the title compound showing 50% displacement ellipsoids.The intramolecular hydrogen bond is shown with dashed lines.

Table 2
Experimental details.